Proliferation of networks, private and public, physical and virtual, has led to an unprecedented access to information, while at the same time, increasing risks of unauthorized access to the networks from various threats, including malware, zero-day attacks, botnets, denial-of-service attempts, and advanced targeted attacks. Moreover, as enterprises consolidate data centers, adopt cloud-services, and virtualize critical infrastructure, they are increasingly seeking ways to unify security management across physical and virtual infrastructures, for example, through comprehensive network security solutions that deliver real-time threat prevention against a wide array of cyber-attacks.